GLib offers mathematical constants such as
G_PI for the value of pi;
many platforms have these in the C library, but some don’t. The GLib
versions always exist.
GDoubleIEEE754 unions are used to
access the sign, mantissa and exponent of IEEE floats and doubles. These unions
are defined as appropriate for a given platform. IEEE floats and doubles are
supported (used for storage) by at least Intel, PPC and Sparc. See
for more information about IEEE number formats.